Method for operating a wind turbine, control system and wind turbine

A method for operating a wind turbine having a rotor with at least two rotor blades, a tower, and a pitch setting system for individually setting pitch angles of the at least two rotor blades, the method comprising:

• providing first information which is representative for bending moments of the at least two rotor blades and assigned positions of the at least two rotor blades;
• providing second information which is representative for maximum allowed bending moments of the at least two rotor blades when the at least two rotor blades are in a critical sector close to the tower;
• determining third information depending on the first and the second information, said third information being representative for whether the bending moment of at least one of the at least two rotor blades exceeds the respective maximum allowed bending moment in the critical sector;
• and,
• if at least one of the at least two rotor blades exceeds the respective maximum allowed bending moment, generating an output signal which is configured to cause the pitch setting system to individually change the pitch angles of the at least two rotor blades in order to reduce a deflection of the at least two rotor blades towards the tower when they pass the tower.

A control device for operating a wind turbine having a rotor with at least two rotor blades, a tower, and a pitch setting system for individually setting pitch angles of the at least two rotor blades, the control device comprising:

• a processor;
• a non-transitory computer readable medium having program code stored thereon;
• said program code being configured, when executed by said processor, to:
• provide first information which is representative for bending moments of the at least two rotor blades and assigned positions of the at least two rotor blades;
• provide second information which is representative for maximum allowed bending moments of the at least two rotor blades when the at least two rotor blades are in a critical sector close to the tower;
• determine third information depending on the first and the second information, said third information being representative for whether the bending moment of at least one of the at least two rotor blades exceeds the respective maximum allowed bending moment in the critical sector;
• and,
• if at least one of the at least two rotor blades exceeds the respective maximum allowed bending moment, generate an output signal which is configured to cause the pitch setting system to individually change the pitch angles of the at least two rotor blades in order to reduce a deflection of the at least two rotor blades towards the tower when they pass the tower.

A control system for operating a wind turbine having a rotor with at least two rotor blades, a tower, and a pitch setting system configured to individually set pitch angles of the at least two rotor blades, the control system comprising:

• a sensor system configured to take measurements via which bending moments of the at least two rotor blades and assigned positions are determinable;
• a control device including a processor and a non-transitory computer readable medium having program code stored thereon;
• said program code being configured, when executed by said processor, to:
• provide first information which is representative for the bending moments of the at least two rotor blades and the assigned positions of the at least two rotor blades;
• provide second information which is representative for maximum allowed bending moments of the at least two rotor blades when the at least two rotor blades are in a critical sector close to the tower;
• determine third information depending on the first and the second information, said third information being representative for whether the bending moment of at least one of the at least two rotor blades exceeds the respective maximum allowed bending moment in the critical sector;
• and,
• if at least one of the at least two rotor blades exceeds the respective maximum allowed bending moment, generate an output signal which is configured to cause the pitch setting system to individually change the pitch angles of the at least two rotor blades in order to reduce a deflection of the at least two rotor blades towards the tower when they pass the tower;
• said control device being signally connectable to said sensor system in order to provide said control device with the measurements of said sensor system;
• and,
• said control device being signally connectable to the pitch setting system in order to provide the pitch setting system with the output signal of said control device so that the pitch setting system individually sets the pitch angles of the at least two rotor blades depending on the output signal.